System of speed control.



C, H. WOODWARD. SYSTEM 0? SPEED CONTROL.

APPLIQATIO-N FlLED OCT. 2|, i9l5.

Patented Nov. 26, 1918.

h/z'iness:

CHARLES H. WODDVJARD, 0F BOURNEMOUTH, ENGLAND.

SYSTEM 0 SPEED CONTRGL.

Specification of Letters latent.

Patented Nov. 26, 1918.

Application filed October 21, 1915. Serial No. 57,161.

To all whom it may concern:

Be it known that I, (EHARLEs H'EMLET \Voonwann, a citizen of the UnitedKingdom of England, residing at 15 Richmond Park Crescent, Bournemouth,in the county of Hampshire, England, have invented a new and usefulSystem of Speed Control, of which the following is a specification.

This invention relates to improvements in speed control systems forrailway trains for use in conjunction with any system of operativecontrol, as, for instance, an air brake system or a control for themotive power applied to the train.

' The object of the invention is to permit a train to proceed at anyspeed under a given limit when running under danger conditions, soconstructed and arranged as to stop the train when the pro-determinedsafety limitof speed is reached or exceeded.

Generally speaking my invention contemplates the use of direct currentfor the purpose of controlling a train and permitting it to proceedunder safety conditions and the use of alternating current to controlthe train to permit it to proceed at a given limited speed under dangerconditions. That is to say,the train may be equipped with the usual orany known direct current train control system which is operative topermit the train to proceed at any desired speed on a safe track, andwhich becomes efiective under danger conditions, as when the trainenters a block which is already occupied by another train, or on, whichthere is an open switch, a broken rail, or the like, to stop or slowdown the train, by opening the release valve of the air brake system, orto cut oil the motive power, or both. In addition to such or likecontrolling systems which may be used, I propose to employ analternating current circuit which is connected to the control device insuch a way that it will assume control of said control device when thespeed of the train has been reduced to a predetermined speed andthereafter permit the train to proceed under danger conditions withinthe predetermined slow speed, but when the train exceeds such limitedspeed under danger conditions the alternating circuit will be efiectiveto permit the control device to be actuated and stop the train. Thealternating current circuit may be supplied by current from a constantvolt alternating current generator that is geared to one of the trainaxles in such a way that the frequency of the alternating currentchanges with the speed of the train and the consequent'variation ofimpedance in the alternating current circuit finally becomes sufiicientto cause the train control device to be operated to stop the train.

In one embodiment of the invention as applied to an air brake system,the release valve of the brake pipe may be held up against its seat,against the action of gravity, by windings in the circuits when saidwindings or either of them are energized, and drops by gravity away fromits seat when the windings are deenergized. In such an arrangement thedirect current circuit winding is operative under safe conditions, andat any speed, to hold the valve against its seat, and the winding of thealternating current circuit is operative to hold the valve against theseat only when the train is traveling at a predetermined slow speed.Therefore, when the valve is released by the direct current winding, itwill open and apply the brakes, unless the train be traveling within therange of speed at which the alternating current winding is operative toassume control of the valve. If the train be running at high speed whenthe valve is openedit will be slowed down by the application of thebrakes until it has attained a speed at which the alternating currentWinding becomes effective to close the valve. The train may therefore beoperated under danger conditions until it exceeds the prescribed limit,whereupon the alternating current winding is deenergized and the valveis opened to apply the brake.

I have shown in the drawing diagrammatically the elements of my noveltrain control system, as applied to a train equipped with an air brakesystem, but it will be understood that the invention is capable ofassumingother specific arrangements and may be applied to other controldevices of the train without departure from the spirit of the claimshereto appended.

In said drawings The figure illustrates one embodiment of my invention.

10, -11 designate respectively the wires from an ordinary train controlcircuit. They are connected to a relay 12 of a local circuit, carried bythe train, in which is included a battery 14 and a winding 15.

16 designates the brake pipe of an air brake system and 17 designates avalve 7 increased i l due which normally seats upwardly against a valveseat 13 in a valve casing 19 that is connected with the pipe in anyusual way. The valve casing is provided below its seat with a lip 20which limits the drop of the valve away from its seat. I

The stem 21 of the valve is prm'ided at its lower end with a core whichoperates in the direct current winding 15. The winding is soproportirmed to the weight of the valve and the core that when. thelocal circuit including the battery ll is closed by the relay 12', thevalve 1? is forced upwardly seat to close the brake pipe. n un isdeenergized the l 1! weight of the valve and the core causes the valvedrop away from its seatand open thchralie pipe to apply the hral Inaddition to the control circuit described, the core 2i wound with nsecond winding The said winding 2 is connected through a circuit ill toa constant volt alternating current generator which is driven. in anysuitable manner from one of the axles of the twin -as, for instance, bymeans of a pulley 2'? fixed and rotating with the axle and connected toshaft of the generator by a belt '29. '1. frequency inipressedupon thecircuit 2% or the constant volt alternating generator is proportioned tothe speed of the train so that the increased impedance caused by the tothe speed of the train, can he used to decrease the lifting effect ofthe wind ng 23 on the core 22 to such an extent u when the train isrunhing beyond a prescribed speed said w ding will be ineffective tohold the valve against the seat.

Normally and under safety conditionsrthe direct current winding; isrelied upon to hold the valve 17 closed. When this condition alters todanger, as when the train enters a hloclt occupied by another train oris modified by other danger conditions, the direct current windingceases to act, whereupon the valve 1.7 opens and the brakes are appliedand this condition continues until. the decreasing speed of the trainreduces the alternating current frequency of: the circuit 2i to a pointat which the alternating current winding 23 operates. Thereupon thebrake valve is again raised to its closed position and the valve willremain closed so as to release the brakes as long as the speed of thetrain is kept below the pre-deteri iined limit. It is clear that anyfailureot the illlXlllfl'fy apparatus will apply the danger condition inthe same way that failure of the main train circuit will. apply orindicate danger conditions.

Moreover I may employ other specific arrangements of releasing valvemechanism for releasing the air from the train pipe in which gravity isnot relied upon to open trains system for f having a dn current controlcirciit and an alternating clnrent control circuit for cmitrolling tl etrain when the direct curient circuit is inoperative, with means to varythe frequency speed of the train to thereby change effectiveness of:impedance in said circuit.

A speed control system for railway trains having; a train controldirectctu'rent control circuit to operate the same for safetyconditions, and an alternating' curr i control circuit having means topermit tno train to proceed at a limited peed under danger conditions.

4.. A speed control systeni for railway ins having a train controldevice with a direct current control circuit to operate the some forsafety conditions, and an alternat ing current control circuit havingmeans to permit the. train to proceed at a'limited speed under dangerconditions with means controlled by the speed of the train to render thealternating current-v control circuit inoperative when the train exceedsa predetermined speed.

5. A speed control system trains having a train control adirect currentcontrol circuit for safety conditions, an alternating current generatordriven by the nioveinent of the train and a circuit supplied by currentfrom said generator and having means to control the train control deviceunder certain speeds of the train when the direct current controlcircuit is inoperative.

6. In speed control system for railway trains, a train control deviceoperative for stopping; the train a direct current circuit forcontrolling said device and an alternating circuit for also'controllingsaid device, with means whereby the frequency of the current of thealternating circuit is controlled by the speed of the train.

7. In a speed control system for railway trains, a train control deviceoperative for stopping the train, a direct current. circuit forcontrolling said device, an alternating current generator driven by themovement of the train and having a circuit for actuating said controldevice, the frequency of 2. A control the of the latter circuit with thedevice with a device, with' to operate it the alternating current beingproportioned to and controlled by the speed of the train.

8. In a speed control system for railway trains, a train stopping andspeed control device and an alternating current circuit for controllingsaid device, with means con trolled by the speed of the train forvarying the frequency of the current of said circuit for the purpose setforth.

9. A speed control system for railway trains equipped with an air brakesystem embracing an air release valve, a magnetizable core connected tothe air valve, a wind ing surrounding said core, with a direct currentcircuit to energlze the Winding, and a second wlnding surrounding thecore, wlth an alternating current circuit in which said second windingis included.

10. A speed control system for railway trains, equipped with an airbrake system embracing an air release valve, a magnetizable coreconnected to the air valve, a winding surrounding said core, with adirect current circuit to'energi'ze the winding, a second windingsurrounding the core, with an alternating current circuit in which saidsecond winding is included, an alternating current generator driven bythe movement pipe which opens by gravity,

of the train for supplying current to said alternating circuit, thefrequency of which is such that the impedance of said alternatingcircuit is raised to such extent that the winding in its circuit becomesinoperative to control said valve when the train exceeds a predeterminedlimit of speed.

11. In a train control system, the combination with an air brake systemincluding a brake pipe, with a release valve in said of a ma ma lzablecore 'comiccted to the ond winding is included, and means to vary thefrequency lII the alternating circuit by the speed of the train wherebythe impedance in the alternating circuit increases to such extent, whenthe train reaches a predetermined speed, as to render said secondWinding lnoperative to control the valve.

O. H. WOODWARD.

Witnesses:

HAR EY J. BAvnRs'rooK, CHARLES PACK.

stem of said-yv valve, a winding surroundlng said core and

